LAUSR

Density and mechanical properties (e.g., compressibility or bulk modulus) are important cellular biophysical markers. As a result, developing a method to separate cells directly based on these properties benefits various applications including biological research, diagnosis, prognosis, and medical therapy. As a potential solution, surface acoustic wave (SAW) based cell separation has demonstrated advantages in terms of biocompatibility and compact device size. However, most SAW-reliant cell separations are achieved using an entangled effect of density, various mechanical properties, and size. In this work, we demonstrate SAW-based separation of cells/particles based on their densities and mechanical properties, irrespective of their sizes. Manipulating the acoustic properties of the fluidic medium allows us to decouple the effects of size from other mechanical properties during the separation process. Using our platform, SAW based separation is achieved by varying the dimensions of the microfluidic channels, the wavelengths of acoustic signals, and the properties of the fluid media in the microfluidic domain. Our method was applied to separate paraformaldehyde-treated and fresh Hela cells based on differences in mechanical properties; a recovery rate of 85% for fixed cells was achieved. It was also applied to separate red blood cells (RBCs) and white blood cells (WBCs) which have different densities. A recovery rate of 80.5% for WBCs was achieved. Owing to its excellent biocompatibility and simple design, our acoustic-based separation method can provide a valuable tool for fundamental research, diagnostics, drug efficacy assessments, and therapeutics.